Issue 4 Model

• Xilinx Artix-7™ A15T FPGA (XC7A15T) implementing:
  • CPU:Z80N CPU with extended instruction set @ 3.5/7/14/28 MHz
  • All standard ZX Spectrum and Timex video-modes with the addition of Layer 2, Layer 3 and LoRes video with 9 bit colour and hardware scrolling
  • TurboSound compatibility (3 PSGs) - 3 x AY-3-8912 or YM-2149 compatible PSG audio chips with stereo output
  • Covox™/Soundrive™/SpecDrum™ compatible digital audio
  • Selectable DMA controller (Z80DMA and zxnDMA)
  • Amiga™ like Copper hardware
  • Hardware Sprite Engine
  • EnhancedULA extending legacy Spectrum and Timex modes to 256 colours out of a 512 colour palette
  • Multiface compatible NMI handling hardware
  • Two programmable UARTs
  • Programmable CTC chip (8 channels)
  • I₂C bus
  • SPI bus
  • PS/2 keyboard and mouse controller
  • Two joystick controllers compatible with Kempston, Sinclair and Cursor standards
  • divMMC interface with an external SD card slot (as well as additional possibility for a secondary internal micro SD card slot, only via expert soldering at user's own risk)
• Memory:2MB SRAM standard
• 58 key laptop-style low profile tactile matrix keyboard
• Video out ports: RGB / VGA Analog and HDMI-compatible Digital Video Port
• Stereo Audio Out port
• Two multipurpose controller and I/O ports for joystick and serial communications
• Tape support, with joint Mic and Ear ports
• Original external bus expansion port
• I₂C RTC (Real Time Clock) device (DS-1307)
• Wi-Fi module, with a full TCP/IP stack (ESP8266).
• Internal accelerator expansion port (for optional Raspberry Pi Zero accelerator)
• On board GPIO for user expansion
• Multicore capability